Prince Charles has been living greener and trimmed his household's carbon emissions significantly, according to an annual review of his accounts.

While the prince has achieved "carbon neutral" status for two years, new initiatives introduced in the last year include:

• Running his luxury cars on used cooking oil.
• Installing wood-chip boilers at his residences.
• Buying foods from local suppliers, according to Charles's Clarence House office.

Prince Charles scaled back his carbon emissions between April 1, 2006, and March 31, 2007 by nine per cent to 3,775 tonnes.
(Barry Batchelor/Associated Press)

Travel abroad accounts for the bulk of his carbon emissions, according to the report. However, he has invested in a carbon offset company — a group that promotes sustainable energy projects as a means of counterbalancing greenhouse gas emissions produced through activity including travelling.

Earlier this year, the prince was criticized after agreeing to travel more than 11,000 kilometres by plane with 20 staff members to accept a Global Environmental Citizen prize from Harvard Medical School's Centre for Health and the Global Environment.

Critics said Charles should have accepted the award via satellite but he refused. Clarence House officials said the prince had cancelled a previously scheduled trip to Switzerland as a means of cutting back on his travel.

Carbon emissions trimmed to 3,775 tonnes

The prince scaled back his carbon emissions between April 1, 2006, and March 31, 2007, by nine per cent to 3,775 tonnes. It's estimated the prince spent about $60,000 US in counterbalancing his carbon carbon emissions.

While more and more companies have vowed to go green, offering their customers carbon offset programs, critics say they fail to change people's consumption patterns.

Advocates of carbon offset programs say they push environmental concerns to the forefront, encouraging consumers to be proactive. They say the offsets actively counterbalance emissions damage by supporting offset projects that include wind farms, tree planting and methane capture plants.

With files from the Associated Press